Manifold with variable length ram pipes



y 1959 c. P. BOLLES, JR 2,894,497

MANIFOLD WITH VARIABLE LENGTH RAM RIPES Filed Aug. 25. 1958 s Sheets-Sheet 1 IN VEN TOR.

July 14, 1959 c. P. BOLLES, JR

MANIFOLD WITH VARIABLE LENGTH RAM PIPES 3 Sheets-Sheet 2 Filed Aug. 25, 1958 IN VEN TOR. (Zak; rf fizzz z. B Y

July 14, 19.5 c. P. BOLLES, JR

MANIFOLD wzm VARIABLE LENGTH RAM PIPES s Sheets-Sheet 3 Filed Aug. 25, 1.958

United States Patent Of MANIFOLD WITH VARIIIASXBLE LENGTH RAM P1P Charles P. 'Bolles, Jr., Dearborn, Mich., assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Application August 25, 1958, Serial No. 757,009

Claims. (Cl. 123-52) This invention relates to an improved type of manifold for a fuel injection system. More specifically, the present invention is an improvement in the resonant type manifold shown in copending application Serial No. 608,935, Dolza, filed September 10, 1956.

As described in the aforenoted Dolza application, it has been found in utilizing a ram tube type manifold, it is possible to select the ram tube length in such a way as to obtain a resonant frequency with respect to the air being inducted into the engine cylinder. This selection of tube length heightens or emphasizes the ram effect and thereby occasions a supercharging effect whereby the volumetric efficiency is maximized at a given engine speed. While such resonance might occur at several diiferent engine speeds, it is usually found that only one of these frequencies occurs at a speed compatible with maximum power output with a fixed length ram tube.

In the Dolza type construction, once having selected the appropriate ram tube length to achieve the resonant frequency at the desired engine speed, for practical purposes -then resonance is not utilizable at any other engine speed. In the present invention a unique type ram tube manifold has been developed which enables the effective ram tube length to be varied under different operating conditions whereby increased volumetric efficiency is obtainable throughout the speed range of the engine or at least at a plurality of engine speeds.

Under low engine speed operating conditions, the frequency of cylinder inlet valve opening is low and correspondingly the frequency or pulsations of the air column within the ram pipes is low. At the same time the time between pulsations is relatively large. Accordingly, under the low speed operating conditions, a relatively long effective ram pipe length is desirable in achieving resonance and hence the supercharging effect noted. On the other hand, during high speed operating conditions, the frequency of inlet valve operation is high and with it the frequency of air column pulsations. In this instance, the time between such pulsations is rather short and correspondingly a shorter effective ram tube length is desirable to achieve a resonant condition.

The present invention, in facilitating variations in effective ram tube length corresponding with changes in engine speed insures a high volumetric efficiency at a plurality of engine speeds and hence contributes to an increased power output for the engine at all engine speeds.

Other objects and advantages of the present invention will be apparent from a perusal of the detailed description which follows.

In the drawings:

Figure l is a partially cross sectioned view of a V- type engine embodying the subject manifold;

Figure 2 is a plan view of the arrangement of Figure 1;

Figure 3 is a view along line 3-3; of Figure 1;

Figure 4 is an enlarged sectional view of the engine speed responsive mechanism for varying the ram pipe lengths;

l 2,894,491 Patented July 14, 1959 Figure 5 is an enlarged sectional view through one of the ram pipes; and 1 Figure 6 is a perspective view of one of the ram pipes as disassembled.

For purposes of illustration the subject manifold arrangement has been shown as embodied on a V-type engine indicated generally at 10. Engine 10 includes a cylinder block portion 12 as well as cylinder heads 14 and 16. The cylinder heads each include a plurality of intake passages 18, in this case four in each head, adapted to deliver a combustible charge to each of the engine cylinders 20. The introduction of the combustible charge into each cylinder is controlled through inlet valves 22. Each cylinder head intake passage 18 communicates with a ram pipe or air intake assembly indicated generally at 24.

A distributor mechanism is shown generally at 26 and,

as shown in Figure 4, includes a shaft 28 driven in prothe overall length of each ram pipe assembly may be varied by angularly inclining the ram pipe from a horizontal. In the form of the invention illustrated the ram pipes are generally horizontally disposed. However, if

longer ram pipes are desired it is apparent that the ram pipes might be inclined upwardly from the horizontal in which event their overall length would be increased. The

desirability for changing the overall length of the ram pipes might vary depending on the particular type of engine upon which the ram pipes are to be mounted.

As seen in Figure 6, each ram pipe assembly 24includes a first tubular member 30 which terminates atone end in a curved section 32 adapted to register with intake passage 18. The remainder of member 30includes a portion 34 of somewhat reduced diameter and which,

construction provides a shoulder 36. Tubular portion-34 includes a plurality of longitudinally extending slots 38.

Each ram pipe assembly 24 also includes a sleeve member 40 adapted to be mounted upon the reduced diametral' portion 34 of member 30 for rotation relative thereto.

Sleeve member 40 seats against shoulder 36. Sleeve 40v also includes a plurality of longitudinallyextending slots 42 corresponding in number to the slots 38 in member 30. While corresponding in number to the slots in member 30 sleeve slots 42 are of a slightly different configuration. Slots 42 differ in that they terminate at their outer or rightmost end, as viewed in Figure 6, in flaredror,

tapered portions 44.

It will be well at this juncture to consider the opera tive relationship between the fixed slots 38 and rotatable sleeve slots 42. As already noted, under low engine speed operating conditions maximum ram pipe'length is desired. Accordingly, under these conditions sleeve 40. should be so positioned with respect to membert30 that the sleeve slots 42 overlie the unslotted portions of the subadjacent portion 34. In this way maximum effective ram pipe length is achieved. Thereafter as engine speed increases it is desired to progressively shortenthe effective length of the ram pipe.

sidered, so that the flared ends 44 of sleeve slots 42 begin to progressively uncover fixed slots 38 in member 30.1 Referring again to Figure 6, it will be apparent that, look-i. ing from the right end of the ram pipe .assemblyfthe aforesaid operation will occur by rotating sleeve 40 in=a counterclockwise direction. Thus as engine speed increases, the effective length of each ram pipe assembly is in effect reduced maintaining a resonant condition and To accomplish this end, sleeve 40 is rotated, by means to be subsequently 6011-."

thereby assuring maximum volumetric efficiency for each engine speed.

Figure 5 represents a sectional view through a ram pipe assembly indicating the position of the respective slots 38 and 42 in which the latter are completely out of registry insuring maximum ram pipe length. It is apparent from this view that as the sleeve 40 is rotated in a counterclockwise direction the sleeve slots 42 will progressively move into registry with fixed slots 38 in member 30 shortening the effective length of the ram pipe.

Inasmuch as it is desired to maintain all of the ram pipe assemblies at the same effective lengths, it is possible to use a common actuating mechanism for rotating the sleeves 40 in unison. As already noted, it is desired to vary the effective ram pipe length inversely with engine speed. Accordingly, it has been found most convenient to utilize the engine distributor mechanism 26 as the means for providing a control force proportional to engine speed.

' As best seen in Figures 3, 5 and 6, a tab member 46 is suitably formed on each ram pipe sleeve 40. A link 48 is articulated at one end to tab 46. The other end of link 48 is articulated to one arm 50' of a bell crank lever 52. Bell crank lever 52 is pivotally supported intermediate its arms upon a bracket 54 in turn supported upon a plate 56 suitably mounted upon cylinder block 12.

A control rod 58 is slidably mounted within a pair of longitudinally spaced supporting brackets 60 and 62 also supported upon plate 56. The other arm 64 of bell crank lever 52 is articulated to control rod 58 through a pin 66 fixed to the control rod. Pin 66 coacts with a slot 68 formed in arm 64 of lever 52. Since control rod 58 reciprocates in a longitudinal direction causing each bell crank lever 52 to rotate about its pivotal connection to bracket 54, it is apparent that a pin and slot type of connection between the lever and control rod is necessary to prevent a binding action between the same.

To achieve a reciprocating movement of control rod 58 whereby ram pipe sleeves 40 will be rotated, supra, one end of the control rod is suitably connected to the distributor mechanism 26. To this end, a bell crank lever 70 is pivotally supported at 72 upon the distributor 26. Lever 70 includes an arm 74 having a slot 76 adapted to receive a pin 78 fixed to the control rod. The other arm 80 of lever 70 likewise includes a slot 82' adapted to receive a pin 84 fixed to a collar 86 slidably mounted upon distributor shaft 28.

At this point it is apparent that as the bell crank lever 70 is rotated about its pivot 72 the longitudinal position of control rod 58 will vary and in turn vary the registry between ram pipe slots 38 and 42. In order that the actuation of the bell crank lever 70 be controlled in accordance with engine speed, collar 86 is articulated through links 88 to a plurality of weighted arms 90 which are in turn articulated at their other ends to a collar 92 fixed to shaft 28 for rotation therewith. It is to be noted that shaft 28 rotates relative to collar 86.

As best seen in Figure 4, as shaft 28 rotates with increased engine speed the weighted arms 90' will be thrown outwardly by centrifugal force. In so moving, arms 90 through links 88 cause collar 86 to be moved upwardly relative to shaft 28. This movement of collar 86 in turn causes a counterclockwise rotation of bell crank lever 70 and through control rod 58 induces a similar counterclockwise rotation to levers 52 controlling the respective ram pipe sleeves 40.

It will be seen that with the above described mechanism it is possible to vary effective ram pipe length inversely to engine speed and thereby maintain a high engine volumetric efi'iciency throughout the engines speed range.

It is apparent that various structural modifications may be made in the illustrated embodiment of the subject invention within the intended scope of the hereinafter appended claims.

I claim:

1. A manifold for an internal combustion engine comprising a plurality of ram pipe devices for respectively supplying air to the individual cylinders of the engine, each of said ram pipe devices comprising a first tubular member mounted upon said engine and communicating at one end with an engine cylinder and open at the other end to atmosphere, a plurality of longitudinally extending slots formed throughout at least a part of the length of said member, a sleeve member rotatably supported upon said first member, said sleeve member including a corresponding number of slots adapted to coact with the slots in said first member, and engine speed responsive means operatively connected to said sleeve members to rotate the latter to progressively move said sleeve slots into registry with the slots in said first member to vary the effective length of each ram pipe device in accordance with engine speed.

2. A manifold for an internal combustion engine comprising a plurality of ram pipe devices for respectively supplying air to the individual cylinders of the engine, each of said ram pipe devices comprising a first tubular member mounted upon said engine and communicating at one end with an engine cylinder and open at the other end to atmosphere, a plurality of longitudinally extending slots formed throughout at least a part of the length of said member, said slots terminating at one end adjacent the atmospheric end of said member, a sleeve member rotatably supported upon said first member, said sleeve member including a corresponding number of slots adapted to coact with the slots in said first member, and engine speed responsive means operatively connected to said sleeve members to rotate the latter to progressively move said sleeve slot means into registry with the slot in said first member to reduce the effective length of each ram pipe device as engine speed increases.

3. A manifold as set forth in claim 2 in which said sleeve slots include a tapered side adapted to coact with a subadjacent slot in the tubular member to progressively uncover the latter slot as engine speed increases.

4. A manifold for an internal combustion engine, said engine including a plurality of cylinders, a cylinder head having a plurality of individual cylinder intake passages, said manifold comprising a plurality of ram pipe devices each adapted to supply air to said cylinder intake passages, each ram pipe device including a first tubular member mounted at one end upon said cylinder head and adapted to communicate with one of said cylinder intake passages, a sleeve member rotatably supported upon said first member, longitudinally extending slot means formed in each of said members, means for rotating said sleeve relative to said first member to vary the amount of registry between said slot means whereby the effective length of each ram pipe device is varied, and a common engine speed responsive device operatively connected to each of said sleeve rotating means to provide unison actuation of said sleeves to maintain all ram pipe devices at substantially the same effective length.

5. A manifold as set forth in claim 4 in which the common engine speed responsive device comprises a pivotally mounted lever disposed adjacent each rotatable sleeve, link means articulated between each sleeve and lever, a common control rod articulated to each lever, and a mechanism operable in proportion to engine speed connected to said rod whereby said sleeves are moved in unison to vary the effective lengths of said ram pipe devices.

No references cited. 

